Date: Sat, 25 Jul 2015 15:25:29 +0200 From: deco33000@yandex.com To: freebsd-hackers@freebsd.org Subject: Timekeeping between two hardclocks Message-ID: <1226791437830729@web8g.yandex.ru>
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Hello, I am learning the freebsd way to keep the time up to date. I already read http://phk.freebsd.dk/pubs/timecounter.pdf I am mostly in sys/kern_tc.c We avoid to call hardware hardclock() every time we need a timestamp by applying some math (to improve performance). I get the idea. But, how do we know how far we are from the last hardclock(), at any given moment? Are the updates to the "fake" timestamps occuring at a constant rate? Is there a feed somewhere I missed? I don't see where in that case. This is the last -and most important- point I don't get on the timer/clock subsystem. I seriously need your help/pointers I guess. Thanks --š Jog
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